Fix the PreferredFilter entry of writer_MWStyle

To silence this thing:

warn:legacy.osl:899:1:filter/source/config/cache/filtercache.cxx:1257:
error: The type "writer_MWStyle" points to an invalid filter "Style (v1)".

Change-Id: If4c01a6a63391e21fd132ba07b05f94bb2679ee4

filter/source/config/fragments/types/writer_MWStyle.xcu

@@ -21,7 +21,7 @@
         <prop oor:name="Extensions"><value>dummy</value></prop>
         <prop oor:name="MediaType"></prop>
         <prop oor:name="Preferred"><value>true</value></prop>
-        <prop oor:name="PreferredFilter"><value>Style (v1)</value></prop>
+        <prop oor:name="PreferredFilter"><value>MWStyle</value></prop>
         <prop oor:name="UIName">
             <value>Style v1 Document</value>
         </prop>